Analysis of traffic congestion costs in a competitive supply chain

We study a competitive facility location problem with identical suppliers competing in multiple markets subject to distribution network congestion. We first analyze the solution of a symmetric competitive location game and discuss the firms’ facility location and equilibrium market supply decisions. Then, we utilize the model to provide analytical characterization of the effects of traffic congestion costs on equilibrium distribution flows. These analytical results permit qualitative characterization of how changes in congestion levels and costs affect equilibrium location and distribution decisions. The results of extensive numerical studies serve to further illustrate the effects of traffic congestion costs on location, market supply quantity, and distribution decisions.     

An empirical assessment of Dutch citizens' preferences for spatial equality in the context of a national transport investment plan

This study presents empirical insights into Dutch citizens' preferences for spatial equality in the context of decision-making regarding the composition of a national transport investment plan. To the best of our knowledge, our study is the first study worldwide which empirically investigates citizens' preferences for the spatial distribution of benefits accruing from a transport investment plan. We conducted two Stated Choice experiments: one involving an investment plan for travel time savings, the other involving an investment plan for traffic safety. Our results show that in the context of travel time savings, a vast majority of citizens has a strong preference for spatial equality. When the investment program involves traffic safety improvements, the share of citizens that has a preference for spatial equality is considerably smaller. Specifically, using a Latent class discrete choice analysis we identified distinct segments. The first segment has a very strong preference for the investment program having the largest total reduction in traffic deaths; the second segment assigns a substantial value to an equal distribution of reductions of traffic deaths across the Netherlands. Highly educated citizens are found to have a relatively strong preference for spatial equality as compared to low educated citizens. Contrary to our expectations, explanatory variables such as political orientation, income, car ownership and region of residence do not appear to associate with citizens' preferences for spatial equality.     

Measuring the economic effects of bilateral liberalization air transport

This paper develops a model that measures the equilibrium changes and welfare consequences of liberalizing the fare, entry and service levels of a bilateral air transport agreement. The model also provides measures of the distribution of gains and losses across the consumers and airlines of each country involved in the bilateral as well as those of any third foreign country that may be affected through traffic diversion as a result of changes in the bilateral. In our model, service quality aspects are treated in the framework of hedonic price theory by specifying the quality-adjusted price (quantity) as a multiplication of the observed price (quantity) by the reciprocal quality index function (the quality index function). The model is illustrated using the Canada–Japan bilateral to assess alternative combinations of changes to fare, frequency and entry restrictions. We report the outcomes for market share, airline profits, fares and consumer welfare.     

网络拓扑结构对交通流量分布特性的影响分析

分析城市交通网络特性,建立双层城市交通网络模型,其中下层为道路网络,上层为出行网络.以节点平均负荷、拥堵节点、网络负荷标准差、基尼系数为主要指标,研究居民出行网络拓扑结构变化过程中道路网络流量分布的变化情况.研究结果显示,出行网络拓扑结构对交通量分布有较大影响,且存在最优出行网络结构,使城市交通状况达到最佳.     

基于可靠性计算的编组站车流预估方法研究

编组站阶段计划作为编组站作业计划的核心,对编组站高效完成运输生产任务具有重要作用。然而编组站阶段计划的编制通常受限于到达车流的时间不确定性和车流信息的不准确性,为提高自动编制阶段计划的准确性,研究一种依据车流实际确报信息对预报信息进行准确性评价、并且根据站内车流和带有准确性评价的到达车流进行车流自动推算的方法。在量化车流可靠性参数评估和列车平均运行时间评估的基础上构建模型,并提出相应的算法,随着系统运行过程中车流信息的不断积累和可靠性评价参数的动态更新,通过模拟调度人员对车流分配的思考过程实现到发车流的自动推算和分配。该方法可以有效提升车流推算的准确程度,提高自动编制的阶段计划的可用性。     

基于重心法与离散模型的配送中心选址研究

采用重心法确定物流配送中心的位置，由于选址因素只包括运输费率和货运量，在实际应用中受到很大限制。为此在用重心法得到备选地点的基础上，引用离散模型解决配送中心的最佳地点问题。结合实例分析，说明基于重心法与离散模型的配送中心选址方法的实际应用。     

Adding a freight network to a national interstate input–output model: a TransNIEMO application for California

The state of the nation’s infrastructure is the subject of widespread discussion and comment because it is thought to include many deteriorating and unsafe bridges. Ever since the terrorist attacks of 9/11, there has been increasing concern over the extent to which an attack on infrastructure could result in serious economic disruption. This research develops a model to analyze the economic consequences of an attack on a major element of the highway network. We add a freight network to a national multiregional economic impact model and make freight traffic flows endogenous. The use of a sub-national interstate model recognizes that most infrastructure planning is at the state level and most political leaders’ interest is local. We base our approach on the National Interstate Economic Model (NIEMO) and refer to an elaboration that we name Transportation network and the National Interstate Economic Model (TransNIEMO). The new model enables us to study the state-specific and industry-specific economic impacts of some significant changes in the nature of highway freight movements. We tested the model for selected freight movements in and out of California. The results are entirely plausible and encourage us to elaborate and test the model for hypothetical disruptions of freight traffic throughout the US.     

An empirically grounded agent based simulator for the air traffic management in the SESAR scenario

In this paper we present a simulator allowing to perform policy experiments relative to the air traffic management. Different SESAR solutions can be implemented in the model to see the reaction of the different stakeholders as well as other relevant metrics (delay, safety, etc). The model describes both the strategic phase associated to the planning of the flight trajectories and the tactical modifications occurring in the en-route phase. An implementation of the model is available as an open-source software and is freely accessible by any user.More specifically, different procedures related to business trajectories and free-routing are tested and we illustrate the capabilities of the model on an airspace which implements these concepts. After performing numerical simulations with the model, we show that in a free-routing scenario the controllers perform less operations but the conflicts are dispersed over a larger portion of the airspace. This can potentially increase the complexity of conflict detection and resolution for controllers.In order to investigate this specific aspect, we consider some metrics used to measure traffic complexity. We first show that in non-free-routing situations our simulator deals with complexity in a way similar to what humans would do. This allows us to be confident that the results of our numerical simulations relative to the free-routing can reasonably forecast how human controllers would behave in this new situation. Specifically, our numerical simulations show that most of the complexity metrics decrease with free-routing, while the few metrics which increase are all linked to the flight level changes. This is a non-trivial result since intuitively the complexity should increase with free-routing because of problematic geometries and more dispersed conflicts over the airspace.     

An origin–destination based road pricing model for static and multi-period traffic assignment problems

To mitigate traffic externalities, we propose an origin–destination (OD) based road pricing model for traffic assignment problems. For elastic demand, we derive explicit optimal tolls for the OD-based pricing scheme. We also extend the model to a multi-period static traffic assignment (MSTA) where we derive analytically the route and OD-dependent tolls based on equilibrium conditions. We present some examples to show that the OD-based tolling scheme could improve the system welfare significantly, compared to the no-toll scenario (user equilibrium – UE).     

Willingness to spend and road pricing rates

Using a theoretical model of urban transport system the paper examines the influence of distribution of willingness to spend within the urban population on road pricing rates. It shows that the rates that must be imposed in an urban area in order to maintain pollutant concentration and congestion due to traffic within acceptable levels is heavily dependent on the distribution of the urban population’s willingness to spend. This fact severely limits the reliability of any method for calculating road pricing rates based on theoretical analysis, so that an experimental approach seems necessary. The paper shows that a relation exists between the toll rate per kilometer of trip and the average traffic congestion, which is typical of each urban area and can be determined experimentally by successively imposing three different rates and measuring the corresponding congestion levels. The relation can then be used to determine the pricing scheme when the purpose of road pricing is to maintain both the congestion and the environmental effects due to urban traffic below acceptable thresholds. An example shows how the model can help policymakers in decision-making processes.     

Freight distribution in megacities: Perspectives of shippers,logistics service providers and carriers

We analyse the opinions of shippers, logistic service providers (LSPs) and carriers related to regulations and issues faced by these companies regarding freight distribution in megacities, and the logistical performance measures likely affected by those regulations and issues. We present a review of the freight distribution literature focusing on a large number of freight distribution aspects, such as regulatory, collaborative, environmental, logistical and risk. We also investigate some logistical performance indicators adopted by the companies. Subsequently, we conduct a survey with 147 companies working in the São Paulo Metropolitan Region (SPMR). We use multivariate analysis of variance to assess the logistical performance indicators and non-linear canonical correlation analysis to identify the most relevant freight distribution attributes. The results that the majority of carriers are located inside the SPMR and efficiently handle these issues better than others actors. The lack of collaboration, cargo theft, traffic congestion and some regulations affect the LSP’s logistical performance. Moreover, the actors perceive regulatory aspects, mainly traffic congestion, and a lack of security for deliveries in unsafe areas as the significant issues for deliveries in megacities.     

The geography of air freight: connections to U.S. metropolitan economies

Despite the rapid growth of air freight shipments, much of the existing literature on the geography of air transportation has paid more attention to passenger travel than air freight. The purpose of this paper is to elevate our understanding of air freight by determining which specific variables most influence and shape the geographic distribution of air freight by metropolitan area using stepwise regression analysis. The empirical results suggest a regression model of five independent variables was the most parsimonious solution where the final model accounted for 71.1% of the variation in air freight shipments by metropolitan area (MA). The most important predictor was the traffic shadow effect, where less populated MAs under the traffic shadow of larger MAs tended to generate lower levels of freight. The model also suggested that other key predictors included the employment market share in transportation-shipping-logistics industries, per capita personal income, the number of medical diagnostic and supplier establishments, and above average wages in high technology. Overall, metropolitan markets with diverse and efficient ground support systems, freight forwarders and other transportation services, a more affluent population, an intense agglomeration of medical laboratories and related suppliers, and a well paid skilled workforce engaged in computer systems design and electronic product manufacturing are more likely to ship freight by air.     

轨道交通系统票务清分算法的研究

随着城市轨道交通的不断发展，同一轨道交通网络中的线路将会由不同的运营商来经营，运营商之间收益的合理分配是城市轨道交通亟待解决的问题。在对实现轨道交通票务清分算法进行分析的基础上，提出有效路径算法。通过计算出OD问的有效路径和不同运营商的线路比例，对收益进行分配，并用清分算例进行实际应用说明。     

Analyzing tactical control strategies for aircraft arrivals at an airport using a queuing model

This paper proposes to analyze control strategies for arrival air traffic at an airport using a classical queuing model. The parameters of our model are estimated by means of a data-driven analysis of two years of radar tracks and flight plans for arrival flights at Tokyo International Airport from 2016 to 2017. Our results show that increasing the capacity with one or two more aircraft in the airspace up to 60 NM around the airport significantly mitigates arrival delays, even when assuming future, increased arrival traffic volumes. The outcomes of this study provide insights into the effectiveness of arrival control strategies and are seen as a means to recommend scenarios to be further analyzed with human-in-the-loop simulations.     

Optimal inter-area coordination of train rescheduling decisions

Railway dispatchers reschedule trains in real-time in order to limit the propagation of disturbances and to regulate traffic in their respective dispatching areas by minimizing the deviation from the off-line timetable. However, the decisions taken in one area may influence the quality and even the feasibility of train schedules in the other areas. Regional control centers coordinate the dispatchers’ work for multiple areas in order to regulate traffic at the global level and to avoid situations of global infeasibility. Differently from the dispatcher problem, the coordination activity of regional control centers is still underinvestigated, even if this activity is a key factor for effective traffic management.This paper studies the problem of coordinating several dispatchers with the objective of driving their behavior towards globally optimal solutions. With our model, a coordinator may impose constraints at the border of each dispatching area. Each dispatcher must then schedule trains in its area by producing a locally feasible solution compliant with the border constraints imposed by the coordinator. The problem faced by the coordinator is therefore a bilevel programming problem in which the variables controlled by the coordinator are the border constraints. We demonstrate that the coordinator problem can be solved to optimality with a branch and bound procedure. The coordination algorithm has been tested on a large real railway network in the Netherlands with busy traffic conditions. Our experimental results show that a proven optimal solution is frequently found for various network divisions within computation times compatible with real-time operations.     

The geographical efficiency of Spain's regional airports: A quantitative analysis

Previous studies of the role of regional airports in the Spanish economy have focused on calculating efficiency using air traffic as the output and airport infrastructure data as the input. We present an alternative quantitative analysis based upon the geographical structure within the airport's market basin. We formulate a ‘geographical efficiency’ model that considers territorial variables within the airport hinterland. Input data for our model include the socio-economic structure of the population, intermodal transport links, industrial and tourism potential and existing leisure-related services. The output is the annual number of passengers associated with such constraints. The result is a relative efficiency estimate that shows uneven patterns of geographical efficiency amongst Spain's regional airports and also provides insights into opportunities for expanding some of these critical items of infrastructure. They suggest that some of Spain's regional airports may be better placed than others to compete in a liberalized market that exhibits a clear tendency in favor of coastal, tourism-based airports.     

Land-use and socio-economics as determinants of traffic emissions and individual exposure to air pollution

This paper presents a modeling framework developed for the City of Montreal, Canada, and is intended to quantify two indicators that can explain the spatial distribution of traffic-related air pollution at a metropolitan level. The indicators are estimated at the level of the traffic analysis zone (TAZ) and include: (1) the average level of emissions generated per individual and (2) the level of emissions occurring in a zone as a proxy for air pollution exposure. A regional traffic assignment model is extended with capabilities for emission modeling at an individual trip level while taking into account vehicle (type and age) and trip attributes (road type, speed, and volume). We observe that individuals who generate higher emissions from travel tend to reside in areas with lower exposure to traffic emissions while individuals associated with low levels of travel emissions (e.g. travel smaller distances, conduct less trips, and use alternative modes) reside in areas with high levels of traffic pollution. A regression analysis of the two indicators against a set of land-use and socio-economic variables shows that generated emissions per individual are positively associated with car ownership and larger vehicles, while being negatively associated with ownership of newer vehicles, and location in dense and walkable neighborhoods with high levels of commercial land-use. Meanwhile, exposure to emissions is positively associated with dense and walkable neighborhoods and negatively associated with car ownership and larger vehicles. These findings indicate major inequities in the generation of and exposure to traffic-related air pollution.     

A delay estimation technique for single and double-track railroads

To route and schedule trains over a large complex network can be computationally intensive. One way to reduce complexity could be to “aggregate” suitable sections of a network. In this paper, we present a simulation-based technique to generate delay estimates over track segments as a function of traffic conditions, as well as network topology. We test our technique by comparing the delay estimates obtained for a network in Los Angeles with the delays obtained from the simulation model developed by Lu et al. [Lu, Q., Dessouky, M.M., Leachman, R.C., 2004. Modeling of train movements through complex networks. ACM Transactions on Modeling and Computer Simulation 14, 48–75], which has been shown to be representative of the real-world delay values. Railway dispatchers could route and schedule freight trains over large networks by using our technique to estimate delay across aggregated network sections.     

A model for time of day and mode choice using error components logit

The severity of road congestion not only depends on the relation between traffic volumes and network capacity, but also on the distribution of car traffic among different time periods during the day. A new error components logit model for the joint choice of time of day and mode is presented, estimated on stated preference data for car and train travellers in The Netherlands. The results indicate that time of day choice in The Netherlands is sensitive to changes in peak travel time and cost and that policies that increase these peak attributes will lead to peak spreading.     

Dynamic road lane management study: A Smart City application

Our Smart City contribution is transportation-oriented in that it proposes a dynamic road lane management system in order to share appropriately the space devoted to traffic. After a historical view of a series of solutions from physical to ICT supported, we present our proposal extensively supported by up-to-date ICT. Following a main presentation, we describe the system architecture and its working conditions. Then, we present the proposed simulator designed to study operating and driver’s conditions with respect to the new traffic signs proposed. We also describe a Mock-up technology validation and give preliminary information on in-the-field deployment.